This invention relates to a cap member having integral gasket retention structure and a method of forming the same. More particularly, this invention relates to the type of cap member used in combination with a container for storing, cleaning and disinfecting contact lenses.
As a result of a public preference for "soft" as opposed to "hard" contact lenses, the required characteristics of lens cases used for storing and treating contact lenses have changed significantly. These changes are due largely in part to the porous nature of the materials used in the formation of "soft" contact lenses which make the task of minimizing the chances of eye infection caused by bacteria growth on the lenses very difficult, and require daily cleaning, disenfecting and sterilization procedures. A widely used method to perform these daily lens care treatments is generally referred to as the "dry heat" method. The "dry heat" method involves immersing the contact lenses in a saline solution which is contained in the base portion of a lens case which is then capped, sealed and placed directly against the heating element of a separate heating unit with means to accomodate the lens case. Sealing the lens case allows the saline solution contained within to become heated above its normal atmosphere boiling point thereby enabling the treatment process to be more efficiently and effectively carried out. It is apparent that a good cap seal is therefore one of the most important elements involved in satisfactorily completing this type of treatment process.
Other disinfecting procedures, such a "cold sterilizing" using hydrogen peroxide also require the use of sealed containers in which the lenses are stored. A reliable cap seal is also essential to this type of procedure.
In the past, proper sealing of a contact lens case was accomplished by providing a suitable gasket in the cap or cover portion of the lens case. To insure the gasket was held properly in place within the cap, a method of sandwiching the gasket between a cover member and a separate disc-like insert was developed. Properly securing the gasket between the two cap parts required protrusions or lugs formed on one cap part to be sent through aperatures formed in the other cap part, and then welding the two parts together thereby trapping the gasket in place. Such a two-piece plus gasket cap device is seen as part of the combination shown in U.S. Pat. No. 4,337,858.
While such prior art devices work well with respect to sealing the lens case, they are possessed of certain conventional shortcomings. In contrast, the gasket retaining cap member and method of forming the same disclosed by the present invention is particularly well adapted for use with the "dry heat" treatment method and others and, as will become fully apparent below, provides for low-cost efficient production using fewer assembly pieces and less assembly time and effort.